Metal-oxide-semiconductor (MOS) transistors are an important type of transistors. A basic structure of the MOS transistors includes a semiconductor substrate, a gate structure disposed on surface of the semiconductor substrate, and source/drain regions located on two sides of the gate structure in the semiconductor substrate. The gate structure includes a gate dielectric layer disposed on the semiconductor substrate and a gate electrode layer disposed on surface of the gate dielectric layer.
A process of fabricating the MOS transistors includes providing a semiconductor substrate, forming a gate structure on surface of the semiconductor substrate, and forming source/drain regions on two sides of the gate structure in the semiconductor substrate.
A back-end process further includes forming an interlayer dielectric layer covering the gate structure and the semiconductor substrate, forming openings (also called through-holes) penetrating the interlayer dielectric layer and exposing a surface of the source/drain regions, and forming conductive plugs in the openings.
As the critical dimension further reduces, the distance between adjacent gate structures decreases, and correspondingly, the distance between the conductive plugs on the source/drain regions and the gate structure decreases. Accordingly, in an MOS transistor, isolation performance between the gate electrode layer and the conductive plugs deteriorates, resulting in deterioration of the electrical properties of the transistor.
The disclosed transistor and fabrication method thereof are directed to at least partially solving one or more problems set forth above and other problems.